Fishing nets and marine stuructures, marine equipment and ships are exposed to long periods of use in water and especially sea water. As a result of this, marine organisms tend to adhere to and proliferate on parts in contact with sea water, and the function of said fishing nets and other equipment may be impaired.
Insofar as concerns fishing nets, stationary nets and culture nets are left in sea water for very long periods of time. Adhesion and proliferation of marine organisms on these nets is particularly serious, so the nets must be replaced frequently and high economic losses are sustained. It is therefore essential to paint these fishing nets with an antifouling paint which makes it difficult for marine organisms to adhere to them.
The marine organisms referred to here which cause such a problem include animal species such as barnacles, hydrozoa, slimy sea squirts, sponges, small polyzoans, skeleton shrimps, hairy polyzoans, sea squirts, serpulas, sea anemones and oysters, and plant species such as sea lettuces, ceramium and green laver. It is also necessary to prevent the adhesion of organic waste or slime originating from the excreta or carcasses of these animal and plant species.
Antifouling paints with addition of silicone oils have been used for this purpose, conventional examples of these silicone oils being dimethyl silicone oil and phenylmodified silicone oil which has improved compatibility with the resin component and chemical components of the paint. However, although these conventional silicone oils conferred satisfactory water repellent peoperties on the paint, their antifouling properties were not so good, and an effective antifouling paint could not therefore be obtained. In conventional antifouling paints, moreover, it was unclear what kind of structure and properties the added silicone oil should have in order to confer good antifouling properties on the resin, and in particular acrylic resin, which is the main component of the paint film. A satisfactory antifouling paint therefore had still not been proposed.
The inventors of the present invention carried out an extensive investigation of the factors affecting the performance of antifouling paints with added silicone oil, and made the following observations:
(1) An organopolysiloxane with suitable coordination power to support the acrylic or other film-forming resin is required. PA1 (2) An organopolysiloxane with intermediate hydrophilic properties with respect to the film-forming resin is most desirable. PA1 (3) If a film-forming resin and liquid resin are used in conjuction, it is desirable that this organopolysiloxane has no interaction with the groups responsible for the cohesive force of the resins. PA1 (A) 100 parts by weight of a film-forming resin, and PA1 (B) 1-50 parts by weight of a chain organopolysiloxane containing oxyalkylene groups and having an HLB of 3-12.
The inventor of this invention then found that excellent results were obtained by the addition of polyether modified silicone oils with a specific hydrophilic lipophilic balance (HLB).